Process for partial oxidation of acetylene



Dec. 15, 1964 J. E. CIOCCHETT] PROCESS FOR PARTIAL OXIDATION OF ACETYLENE Filed Feb. 9, 1960 llldllllllllllllll'l lllllllllllllllllllllllllllll lillilll 0!IAft)!v: l)!Illlirltllllillllltl m I c INVENTOR JOHN CIOCCHETTI WW, 4% v BQ ATTORNEYS.

United States Patent ()fifice 3,161,683 Patented Dec. 15, 1964 3,161,683 PROCESS FOR PARTIAL OXIDATEON OF ACETYLENE John E. Ciocchetti, Armenia, Colombia, assignor to Acidos Grasos Limitada, Armenia (Caldas), Colombia Filed Feb. 9, 1960, Ser. No. 7,699 15 Claims. (Cl. 260585.5)

This invention relates to the partial oxidation of acetylene and it has particular relation to the preparation of ketene by partial oxidation of acetylene by means of air.

It is a principal object of the present invention to react acetylene with air according to the scheme H This reaction is on the whole endothermic, because the heat released by oxidation is not suificient to balance the energy necessary for separation of the hydrogenation and for splitting the oxygen molecule.

As well as providing a process for reaction (I), the applicant herein provides a catalyst for diminution of the activation energy and of the temperature necessary for producing the desired reaction with satisfactory yields. This catalyst and a process for its preparation are described and claimed in divisional application Serial No. 114,013, filed June 1, 1961.

Other objects and the advantages of the invention will be apparent from the following description and claims.

It has been found that the above mentioned reaction according to Scheme I can be carried out in satisfactory manner at relatively low temperatures with good yield in the presence of a silver oxide catalyst prepared in the manner described hereinafter.

The catalyst used according to the present invention consists of silver oxide deposited on a silica gel base consisting of the precipitate obtained by adding an acidified zinc chloride solution and a calcium chloride solution to a sodium silicate solution. In carrying out the present invention, the use of silica gel as the catalyst carrier is pre ferred, but the silver oxide catalyst used according to this invention can be deposited also on an andesine base or on an anorthite base in the manner described hereinafter. The andesine is a calcuim feldspar having the formula (CaNa=)OAl O 4SiO and the anorthite is a calcium feldspar of the formula (CaOAl O 2SiO In order to prepare the silver oxide catalyst on the beforementioned gel carrier the following procedure can be 966 ml. of an aqueous sodium silicate solution, which contains Sit), and Na,0 in a ratio of SiO,/Na==3.22 and 37.8% of digolvede-material based on the weight of the total solution, are dissolued in 1800 ml. of water.

A first solution of 68 grams of zinc chloride dissolved in 1300 ml. of water containing 30 ml. of 4 N aqueous solution of hydrochloric acid, and a second solution of 109 grams of calcium chloride dissolved in 1200 ml. of water, are then introduced under vigorous stirring into the sodium silicate solution and the resulting mixture is poured into a container, which is large enough to contain the resulting gel in a layer having a thickness of about one centimeter. After standing forbout 2 hours, the gel is cut into small cubes of aboutd' 1 x 1 cm. and allowed to stand for two days. The cubes are then transferred to a Buchner funnel and washed therein during about 3% hours with 8000 ml. of a 2% aqueous solution of zinc chloride. They are then washed with water, dried at 150 C. for about 4 hours and finally calcined in a mufiie at SSW-600 for about hours, so that the cubes will be reduced to pellets of 4 X 4 x 4 mm.

In order to precipitate the silver oxide on the cubes of carrier thus prepared, said cubes are placed in a 2-liter Erlenmeyer flask having an evacuation pipe on the side of the neck. A stopper provided with a bore is inserted in said flask and a glass tube is inserted in said bore, is connected by means of a flexible tube with a funnel pro vided with a stop-cock so that the funnel is placed on the top of the flask. About 1000 ml. of 0.165 N silver nitrate solution are now introduced into the funnel, a vacuum is produced in the flask and 920 ml. of the silver nitrate solution are admitted into the flask, whereupon the cock is closed. The remainder of the silver nitrate solution is then poured otT, the funnel washed and 20 mlco'f 28% aqueous ammonia are introduced into the funnel. 15 ml. of the ammonia solution are then gradually admitted to the flask while shaking the flask. After closing the cock, 260 ml. of a 0.7 N solution of aqueous NaOH and 8 ml. of 28% aqueous ammonia are introduced into the funnel. The liquid mixture in the funnel is now gradually admitted to the flask under shaking. After standing for about A hour the vacuum in the flask is terminated and the contents of the flask are introduced into a Buchner funnel to allow the liquid to drain. The resulting material is dried at 150 C. for about 4 hours and finally calcined at 360 C. for about 8 hours. The material thus obtained is then used as a catalyst in the manner described hereinafter.

Precipitation of the silver oxide on the andesine or anorthite carrier and preparation of the catalyst distributed on these carriers is carried out as follows.

400 grams of the carrier ground to pieces which pass through a 20smesh screen, are introduced-into a 3-liter Erlenmeyer flask provided with a pipe arranged on the side of the neck.- The flask is provided with a stopper having a bore, in which a glass tube in introduced and this glass tube is connectedv with the tube of a funnel which contains a solution of gramsof zinc chloride in 1300 ml. of water and is placed on top of the Erlenmeyer flask. After producing a vacuum in the flask, about 1200 ml. of thezinc chloride solution is admitted to the flask by opening the cock olj the funneL As soon as 1200 ml. of the zinc chloride solution are introduced into the flask, the cock of the funnel is closed and the remainder of the zinc chloride solution is poured oil. The funnel is then washed and 8 ml. of 28% aqueous ammonia solution and ml. of water are introduced into the funnel. Then,,by opening the cock of the funnel, the ammonia is introduced into the flask under vigorous shaking. i

After standing for about to hour, air is admitted to the flask and its contents are discharged into a Buckner funnel in order to allow the excess liquid to drain. The material is then dried for about 4 hours at C. formed topelletsof4x4x4mm.andfinallycalcinedatabout 550 C. for 10 hours. 7 j v Precipitation of the silver oxide on the andesine or anorthite carrier or base is carried out in the manner described above in connection with the precipitation on the silica gel carrier.

The reaction according to the above Scheme 1 can be carried out preferably in reactors consisting of two coaxial tubes. The catalyst is placed in the space between the two tubes so as to fill somewhat more than half of this space Acetylene is passed through this space whereby air is introduced into the acetylene through the center tube. The air should be admitted into the acetylene in small quantities so that the air content of the acetylene does not exceed-about 20% by volume, or expressed in other terms, so that the amount of oxygen present in the acetylene-air mixture does not exceed about 5 parts by volume per 100 parts acetylene. In order to introduce the air into the reaction space, the central tube must be provided with the necessary number of suitably dimensioncd holes suitably spaced relative to each other. The

reaction can be carried out in the temperature range of 98 to 220 C. and the optimum reaction temperature is 98 -l07 C.

During one passage through a reactor which has a length of three meters, is formed by a center tube of 6 to mm. diameter and an outer tube of 30 to 40 mm. diameter, a conversion of the acetylene of up to 55% is obtained, whereby 4 to 6 liters of acetylene mixed with air are passed through the reactor and the catalyst, at a temperature of 98-100 (3., during 1 second.

The gases discharged from the reactor are immediately cooled and the ketene is made to react with acetic acid or an alcohol to produce acetic anhydride or an acetic acid ester. Or the gases are absorbed in a limited quantity of acetone, in which the ketene dimerizes readily to diketene (13.1. 127 C.) which will absorb the subsequently in coming ketene. After a short period of time, there will be a greater quantity of diketene than acetone in the absorption vessel so that only the ketene will be absorbed with a very small quantity of acetylene, while the excess of acetylene can be recycled. The carbon dioxide which may have been formed is absorbed by NaOH solution before the acetylene is recycled.

It will be understood that the above examples represent specific embodiments of and a best mode for carrying out the invention, to which the invention is not limited.

The appended drawings diagrammatically illustrate reactors for carrying out the process of this invention. FIGURE 1 illustrates an individual reactor and FIG. 2 illustrates an assembly of several individual reactors.

In FIGURE 1 the central tube for introduction of the air is denoted by reference symbol 1, the outer tube is denoted 2, the reaction space 3 and the silver oxide catalyst 4. The reaction temperature is maintained by suitable conventional heating means (not shown in FIG. 1). The center tube and outer tube may consistof any suitable material, such as common steel, 'or'prefcrably steel. The center tube may have an inner diameter of 10 mm. and the outer tube an inner diameter of 40 mm. and the length of the reactor tube system may vary eLg. between two and three meters. r

by air, but other mixtures of oxygen and nitrogen which are similar to air can likewise be used. The term air is, therefore, used herein to include such mixtures too.

It will be understood from the above that this invention is not limited to the specific steps, conditions, arrangements and other details specifically described above and illustrated in the drawings and can be carried out with various modifications without departing from the scope of the invention, as defined in the appended claims.

The parts and percent stated herein are by weight if not otherwise stated. The term ZO-mesh screen is used herein to denote a screen having 20 meshes in 1" length,

the free space per mesh being about 0.83 mm.

What is claimed is:

1. A process for the partial oxidation of acetylene to ketene by air, comprising reacting acetylene with air'in the presence of a catalyst which is free from moisture and which is selected from the group consisting of (a) silica gel containing zinc oxide and calcium oxide and having silver oxide distributed thereon, and (b) calcium feldspar containing zinc oxide and having silveroxide distributed thereon, said catalyst containing silver oxide in the amount in the range of from about 610% by weight, zinc oxide in the amount in the range of from about 8-10% by weight, and calcium oxide in the amount in the range of from about 10-15% by weight at a temperature in the range of 98 to 220 C.

2. The process according to claim 1 wherein said catalyst is silica gel containing zinc oxide and calcium oxide and having silver oxide .distributed thereon.

3. The process according to claim 2 wherein said silica gel is formed by precipitation of an aqueous sodium silicate solution with an acidified solution of zinc chloride and a solution of calcium chloride. 7

4. The processaccording to claim I wherein said catalyst is calcium feldspar-containingzinc oxide and having silver oxide distributed thereon.

5. The process according to claim 4 wherein said calcium feldspar is andesine.

6. The process according to claim 4 wherein said calcium feldspar isanorthite.

In practice, a number of individual reactors may be:

mounted in an appropriate common enclosure 20, as shown, by way of example in the appended FIG.- 2. In the latter, the air supply tube 1 of each individual reactor is connected to an air-supplying vemel 5 and supplies air through holes in to the reaction space 3. Acetylene is fed to the reaction space 3 of each individual reactor through separate tubes 6 and the gaseous reaction mixture is discharged from each individual reactor through separate dis charge tubes 8 through which the acetylene-ketene containing mixture is led to the cooling and absorption device (not shown in the drawing)" In order to obtain e'ven distribution of acetylene in the reaction mace, there is a space 10 provided at the right end (in the drawing) of each reactor tube 2, said spacg being separated from the catalyst 4 by grid 11, supporting the catalyst. Into the free spaces between the individual reactor tubes 2 a heating medium is introduced through tube 7 into enclosure or casing 20 and is discharged from the'latter through tube 9. As a heating medium Dowtherm A gave very satisfac- V tory results. According to, the present invention, instead of the feldspar-s named abfive, other calcium feldspars can also be used. The abse ce oi moisture in the carrier and the presence of zinc oxide and calcium oxide therein are necessary for successfully carrying out the invention. The silver oxide should be present in the catalyst-l-carrier mixture in an amount in the range of 640% and the zinc oxide should be present in an amount of 53-10% and the calcium oxide in an amount of 10-15%, in the catalyst-{- carrier mixture.

The minimum concentration, in which oxygen (in the form of air) should be present in the reaction mixture is 1 volume of oxygen for 100 volumes of acetylene. Oxidation of the acetylene according to this invention is effected 7. The process according to claim 1 wherein said air,

provides-an amount of oxygen in the range of from about 1 to about 5 parts by volume per parts of said acet ylenc. I

8. The process according to claim 1 wherein'said tem- .peramre is in the range of from about 98 to about 107 C.

9. A process for the partial oxidation of acetylene to ketene comprising reacting acetylene with an amotmt of air providing from about 1 to about 5 parts oxygen by volume per parts acetylene, at a temperature in the range of from about 98 to about 220 C. in the presence of a catalyst selected from the'group consisting of (a) silica gel containing zinc oxide and calcium oxide and having silver oxide distributed 'thercom-and (b) calcium feldspar containing zinc oxide and having silver oxide distributed thereon, said catalyst being free from moisture and containing silver oxide in an amount in the range of from about 6 to about 10% by weight, zinc oxide in an amount in the range of from about 8 to about 10% by weight, and calcium oxide in an amount in the range of from about 10 to about 15% byweight.

10. The process according to claim 9 wherein said 14. The process according to claim 12 wherein said calcium feldspar is anorthite.

15. The process according to claim 9 wherein said temperature is in the range of from about 98 to about 107 C.

1,773,970 Dreyfus Aug. 26, 1930 Hull 12111.29, 1946 10 6 2,565,627 Pryor Aug. 28, 1951 2,636,898 Buckley Apr. 28, 1953 2,685,569 Nicholson et a1. Aug. 3, 1954 2,806,064 McKlveen Sept. 10, 1957 2,820,058 Luke et al Jan, 14, 1958 OTHER REFERENCES Bludworth: Oil and Gas Journal, vol. 46, No. 51, pages 99-103 (1948).

Groggins: Unit Processes in Organic Synthesis (5th edition) p. 497 (1958). 

1. A PROCESS FOR THE PARTIAL OXIDATION OF ACETYLENE TO KETENE BY AIR, COMPRISING REACTING ACETYLENE WITH AIR IN THE PRESENCE OF A CATALYST WHICH IS FREE FROM MOISTURE AND WHICH IS SELECTED FROM THE GROUP CONSISTING OF (A) SILICA GEL CONTTAINING ZINC OXIDE AND CALCIUM OXIDE AND HAVING SILVER OXIDE DISTRIBUTED THEREON, AND (B) CALCIUM FELDSPAR CONTAINING ZINC OXIDE AND HAVING SILVER OXIDE DISTRIBUTED THEREON, SAID CATALYST CONTAINING SILVER OXIDE IN THE AMOUNT IN THE RANGE OF FROM ABOUT 6-10% BY WEIGHT, ZINC OXIDE IN THE AMOUNT IN THE RANGE OF FROM ABOUT 8-10% BY WEIGHT, AND CALCIUM OXIDE IN THE AMOUNT IN THE RANGE OF FROM ABOUT 10-15% BY WEIGHT AT A TEMPERATURE IN THE RANGE OF 98* TO 220*C. 